For the first time, German researchers have demonstrated that exposure to house dust endotoxin is associated with a lower prevalence of allergic sensitization in school children. The researchers compared the effects of house dust endotoxins on different degrees of allergic sensitization in 444 boys and girls aged 5 to 10 years. (Endotoxins, present as common constituents of house dust, are cell wall components of the outer membrane of gram-negative bacteria. They are known to have both strong immuno-stimulatory and pro-inflammatory properties.) The investigators found that exposure to higher levels of house dust endotoxin in particular decreases the risk of more severe sensitization. They revealed that children who had lived in the same house since birth showed stronger endotoxin effects on sensitization to any allergen than did those who had moved. They believe that living in the same home offers a better estimate of endotoxin exposure in early life. Fifty percent of the children were either atopic (had an inherited tendency toward allergy), or had a physician diagnosis of asthma. Blood samples from each child and dust samples from the living room floor of each house were available for all participants. The research appears in the first issue for October 2002 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
FEMALES MORE COUGH SENSITIVE THAN MALES
Researchers testing the responses of both sexes to tussive agents showed that cough sensitivity was greater in females than males at a clinic for chronic cough. Investigators tested a total of 118 patients, including 68 females and 50 males, with inhalation cough challenges. The inhalation cough challenge materials were inhaled through a mouthpiece for 1 second and the number of coughs in the first 10 seconds after inhalation were recorded. The researchers used inhaled capsaicin, a white crystalline extract of red pepper, and citric acid to cause coughing. Measurements of each successive cough challenge were significantly lower for female patients when compared with male. Cigarette smoking and the type of cough being treated did not influence the results. The investigators noted that this study of a large group of patients with chronic cough has shown for the first time that women compared with men have a heightened cough reflex sensitivity to both capsaicin and citric acid cough challenges. A similar difference between the sexes was also seen in the clinic for two principal diagnostic categories, asthma and gastroesophageal reflux disease. The study was published in the first issue for October 2002 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
OCCUPATIONAL AIRBORNE EXPOSURE RAISES INCIDENCE OF RESPIRATORY SYMPTOMS AND ASTHMA
In a Norwegian study of 2,819 subjects over an 11-year period, researchers found that there was an increased risk of developing respiratory symptoms and asthma if participants were exposed to dust and fumes in the workplace. The investigators showed the association between occupational exposure and respiratory symptoms and asthma, even after adjusting for sex, age, educational levels, and smoking habits. The researchers also discovered that quartz exposure caused cough symptoms and asbestos exposure led to high risk of severe breathlessness and asthma. Slightly over 28 percent of the participants were exposed to dust and fumes in the workplace, with 3.7 percent exposed to quartz, and 5 percent inhaling asbestos. Between 5.7 percent and 19.3 percent of the incidence of respiratory symptoms and 14.4 percent of the incidence of asthma were attributable to dust and fumes exposure. In 1985, the original sample involved 3,370 subjects in the city of Bergen and 11 surrounding municipalities in western Norway. The participants answered a 40-question survey on respiratory symptoms, asthma, smoking habits, and airborne exposure in the workplace. In late 1996, 2,819 of the original respondents returned a 58-question survey on the same topics with the wording of the questions on symptoms identical to the first questionnaire.
The research results appear in the first issue for October 2002 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
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